1. Field of the Invention
The present invention relates to a liquid droplet ejecting device, an image forming apparatus, and a method for detecting abnormal ejection of a liquid droplet ejecting head.
2. Description of the Related Art
Inkjet printers can form desired characters and figures on a recording medium (e.g., paper, metal, wood, or ceramics) using an inkjet recording head that includes, for example, a nozzle for ejecting ink droplets, a pressure chamber that is in communication with the nozzle, and a piezoelectric element for applying pressure to ink within the pressure chamber.
The recording head of an inkjet printer has a plurality of nozzles for ejecting ink droplets. However, when one or more of the nozzles become clogged due to drying of the nozzles, thickening (increased viscosity) of the ink within the pressure chamber, or bubbles entering the pressure chamber, for example, the nozzles may be unable to eject ink droplets and a printed image may have missing dots to thereby result in image quality degradation.
Particularly, in continuous feed inkjet printers that can form an image at high speed by continuously applying a drive waveform to a recording head, when image quality is degraded due to nozzle clogging such that a resulting printed product fails to meet desired print quality, printing will have to be performed all over again to have a huge impact on productivity, for example.
Thus, techniques are known for detecting nozzle clogging, such as residual oscillation detection. In residual oscillation detection, oscillation of a nozzle surface (hereinafter referred to as “meniscus”) after ink droplet ejection is propagated and the state of the meniscus is detected based on a change in the oscillation pattern of a counter electromotive voltage that is generated.
For example, Japanese Unexamined Patent Publication No. 2015-47803 describes an example nozzle clogging detection method using the residual oscillation detection technique that involves setting the period of a residual oscillation waveform as a parameter to detect nozzle clogging.